Propellant composition of the nitrocellulose type containing non lead-containing ballistic modifiers

ABSTRACT

Barium salicylate and/or other organobarium salts, barium oxide, and organometallic salts of lanthanum, hafnium, and tantalum and oxides of the same are used as ballistic modifying means for solid propellants. The specific ballistic modifying means can be used as replacements for the lead, copper, etc., compounds currently employed as ballistic modifiers in solid propellants. The propellants containing the specified ballistic modifying means retain the highly desirable plateau-burning characteristics, pressure exponents, and temperature coefficients but are particularly attractive because they produce considerably less smoke during the burning thereof.

United States Patent Sayles Jan. 14, 1975 [5 4] PROPELLANT COMPOSITIONOF THE NITROCELLULOSE TYPE CONTAINING NON LEAD-CONTAINING BALLISTICMODIFIERS Inventor: David C. Sayles, Huntsville, Ala.

Assignee: The United States of America as represented by the Secretaryof the Army, Washington, DC.

Filed: Feb. 9, 1970 Appl. No.: 14,822

US. Cl 149/l9.8, 149/92, 149/98, 149/100 Int. Cl C06b 3/02 Field ofSearch 149/19, 20, 38, 100, 92, 149/94, 95, 96, 97, 98, 19.8

References Cited UNITED STATES PATENTS 3,138,499 6/1964 Camp et a1.149/38 3,228,338 1/1966 McEwan et all... 3,228,815 l/l966 Henry et a1.[49/98 [57] ABSTRACT Barium salicylate and/or other organobarium salts,barium oxide, and organometallic salts of lanthanum, hafnium, andtantalum and oxides of the same are used as ballistic modifying meansfor solid propellants. The specific ballistic modifying means can beused as replacements for the lead, copper, etc., compounds currentlyemployed as ballistic modifiers in solid propellants. The propellantscontaining the specified ballistic modifying means retain the highlydesirable plateau-burning characteristics, pressure exponents, andtemperature coefficients but are particularly attractive because theyproduce considerably less smoke during the burning thereof.

7 Claims, N0 Drawings NON LEAD-CONTAINING 'BALLISTIC MODIFI'ERSBACKGROUND OF THE INVENTION Lead based compounds have-been utilized inpropellant formulations to provide a number of desirable ballisticeffects. One such very desirable ballistic effect is to provide stableburning of the propellant over a time period to yield a relativeconstant volume of discharged gases from the burning propellant which isindependent of the pressure. The described phenomenon is commonlyreferred to as mesa or plateau-burning.

The lead based ballistic modifiers, although very acceptable for theirfunction in producing plateauburning characteristics, do constitute asignificant source of smoke which causes visual interference inline-of-sight unguided, direct-fire guided weapons. The amounts of smokewhich in past times were considered tolerable are proving a severehandicap because of target obscuration. In particular, the lead oxidespresent in exhaust gases from propellant are easily observed againstcertain backgrounds because of their white or bluish-white color.

Thus, a need exists for ballistic modifying means which produce markedlyless smoke while at the same time maintain the highly desirableplateau-burning characteristics, pressure exponents, and temperaturecoefficients.

The object of this invention is to provide non-leadcontaining ballisticmodifying means which are suitable replacements for commonly used, leadbased ballistic modifiers.

Another object is to provide propellant compositions with minimumsmokelessness.

SUMMARY OF THE INVENTION Organometallic salts of lanthanum, hafnium,tantalum, and barium are used to replace lead salts, such as,lead-beta-resorcylate, and lead salicylate, in solid propellants of thenitrocellulosic type composition. Oxides of the specified metals may beused to replace the lead oxide in a conventional 30/70 blend of leadoxide and stannic oxide employed in solid propellants of thenitrocellulosic type composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Barium salicylate and bariumbeta-resorcylate in equal amounts by weight may be used in solidpropellant compositions as a replacement of the like salts containinglead. The lead salts are generally employed as ballistic modifiers up toabout 5 weight percent of the solid propellant formulations. Bariumoxide may also be used with stannic oxide in place of lead oxide insolid propellant formulations. Oxides or organometallic compounds of themetals lanthanum, hafnium, and tantalum may be used also in a likemanner.

Table I and Table II, below, set forth formulations wherein lead saltshave been replaced with the barium salts listed therein. Inasmuch as thelead compounds contribute an amount of smoke which is about equal to orsomewhat greater than that of the double-base matrix, a significantamount of smoke reduction results from the replacement of lead compoundswith barium, lanthanum, hafnium, or tantalum compounds.

TABLE 'I PROPEIiLANT FORMULATION By Weight INGREDIENT Lead- Non-LeadContaining Containing Control (A) Novel (A) Nitrocellulose 49.9 50.25Nitroglycerine 36.4 36.66 Triacetin 8.0 8.06 2-nitrodiphenylamine 1.7 l.7 1 Lead salicylate 2.0 Lead-betwresorcylate 2 0 Barium salicylate [.66Barium beta-resorcylate l.66

TOTALS 1000 I000 TABLE II PROPELLANT FORMULATION By Weight INGREDIENTLead- Non-Lead Containing Containing Control (B) Novel (B) CastingPower* ll.75 l L79 Casting Solvent* 43.56 43.68 Trimethylenctrinitramine39.52 39.63 30/70 Pb O /SnO 3.94 Toluene diisocyanate 0.74 0.75Resorcinol 0.49 0.50 30/70 BaO/SnO or BaO /SnO, 3.65 TOTALS l00.00l00.00

**Triethylene glycol dinitrate 28.7 parts or about 28.4 percent byweight of the propellant composition.

Butane triol trinitrate 15.0 parts or about 14.9 percent by weight olthepropellant composition.

Z-nitmdiphenylamine 0.4 parts or about 0.4 percent by weight of the-propellant composition.

The nitrocellulosic propellant (Novel B) set forth above contains about83.9 percent by weight oxidizer plasticizer means, about 10.6 percent byweight nitrocellulose binder-fuel, about 1.1 percent by weightstabilizer, about 0.75 percent by weight cross-linking agent, and about3.7 percent by weight of metallic oxide ballistic modifying means.

The metal containing ballistic modifying means in Novel A and Novel Bpropellant is less by weight since the substitution is made on a molefor mole basis. Therefore, the weight percent of each other ingredientin the propellant formulations increases accordingly, and the weightpercent of the metal containing ballistic modifying means wherein leadhas been replaced decreases for the reason stated.

The nitrocellulosic propellants of this invention employoxidizer-plasticizer means in amounts from about 36 to about 84 percentby weight of the propellant, ni-

trocellulose binder-fuel in amounts from about 10 to about 50 percent byweight of the propellant, stabilizer in amounts from about 1 to about 2percent by weight of the propellant, ballistic modifying means inamounts from about 2 to about 5 percent by weight of the propellant, andcross-linking agent in amounts from about 0.75 to about 8 percent byweight of the propellant.

long as uniformity of mix is assured.

The formulations of Table II illustrate how barium oxide is used toreplace lead oxide in the blended oxide containing lead and stannicoxides. Similarly, the oxides or the organometallic salts of lanthanum,hafnium, and tantalum may be used to replace the lead compounds whichare employed as ballistic modifying The directions for preparing therepresentative organometallic compounds are set forth below using theorganobarium compounds as examples. Similarly, organometallic compoundsof lanthanum, hafnium, and tantalum may be prepared by using theequivalent mole quantities of the respective metal salts of the desiredorganometallic compound to be prepared.

SYNTHESIS OF BASIC BARIUM BETA-RESORCYLIATE Barium acetate monohydrate(0.05 mole., 12.8 gms) was dissolved in warm water (70 ml), and aqueoussodium hydroxide (0.10 moles, 4.0 gms in 70 ml water) was graduallyadded with stirring. After settling had occurred, the barium hydroxidewas washed by decantation with distilled water several times, and usedimmediately in the next step of the synthesis.

Beta-resorcinol (0.03 moles, 3.3 gms.) was dissolved in water (270 ml)by means of vigorous agitation. The reaction mixture was heated to 90C,and the barium hydroxide, previously prepared was introduced in smallportions. Agitation at 90C was continued for 3 hours. The basic bariumsalt was washed once by decantation and again on the filter withalcohol. The residue was dried in a vacuum desiccator using anhydrouscalcium chloride as the desiccant.

SYNTHESIS OF BARIUM SALICYLATE To prepare barium salicylate, the sameprocedure for the preparation of barium hydroxide, as described above,was used. Salicylic acid (0.06 moles, 8.3 gms) was dissolved in water(300 ml) with agitation. The reaction mixture was heated to 70C, and thebarium hydroxide, previously prepared, was introduced in small portions.After the addition was complete, the reaction mixture was maintained at70C, and stirred an additional hour. The barium disalicylate salt waswashed by decantation, then filtered and washed with alcohol. Theresidue was dried in a vacuum desiccator using anhydrous calciumchloride as the desiccant.

Burning rate data and transmissibility data are set forth in Table IIIbelow. The burning rate data was obtained on uncured propellant slurrieson S-gm batches. The uncured propellant was burned in a micro-windowbomb under mitrogen. The slurries were prepared by means of a high speedmixer and .degassed before loading in plastic straws (0.155 to 0.157 in.diameter). The straws were burned at two pressures and duplicatedeterminations were made at each pressure.-

A comparison of barium and lead salts in identical propellant slurriesshow the barium salts to be as effective as the lead salts at pressuresranging from 750 psi to 1250 psi on a mole-percent basis and to produceexhaust products of considerably greater transmissibility.

Table III below sets forth burning rates and transmissibilitymeasurements for the propellants, Control (A) and Novel (A) of Table Ihereinabove.

TABLE III COMPARISON OF PROPELLANTS CONTAINING DIFFERENT ORGANO-METALLICSALTS Control Novel Burning- Rate (at 750 psi) (ips) 0.63 0.66 (at 1000psi) (ips) 0.80 0.70 (at 1250 psi) (ips) 0.83 0.82 Transmissibility...-30 56 Typically, the nitrocellulosic variety of propellants, Examples Iand II, are comprised of a stabilizer such as 2- nitrodiphenylamine andresorcinol, an oxidizer plasticizer means such as nitroglycerine,triethylene glycol dinitrate, butanetriol trinitrate, andtrimethylenetrinitramine, nitrocellulose binder fuel, a cross-linkingagent such as toluene diisocyanate, or triacetin, and selected ballisticmodifying means for specific functions.

The smokeless variety of propellants which contain lead salts have beenacceptable under certain environments and backgrounds: however, the leadoxides in the exhaust gases contribute a white or bluish-whiteappearance which is to be avoided under more rigid requirements andcontrols. Thus, the metallic compounds used as lead compoundreplacements in accordance with this invention are very attractive wherea higher degree of smokelessness is required for present day militarytactical weaponry.

I claim:

1. In a propellant composition classified as a smokeless type propellantof the nitrocellulosic variety employing ballistic additives, theimprovement in smokelessness of said propellant composition achieved byemploying ballistic additives in the form of metallic compounds in saidcomposition, said metallic compounds being selected from the groupconsisting of organometallic salts of lanthanum, hafnium, tantalum, andbarium and oxides of lanthanum, hafnium, tantalum, and barium.

2. In a propellant composition of the type specified in claim 1 andwherein said metallic compounds selected are barium salicylate andbarium betaresorcylate in equal amounts up to about 5 weight percent ofsaid composition.

3. In a propellant composition of the type specified in claim 1 andwherein said metallic compounds selected are barium oxides, BaO or BaOwhich are employed in a 30/70 ratio with stannic oxide, and which areemployed in amounts up to about 5 weight percent of said composition.

4. A nitrocellulosic propellant comprised of oxidizerplasticizer meansselected from nitroglycerine, triethylene glycol dinitrate, butane trio]trinitrate, and trimethylenetrinitramine, nitrocellulose binder-fuel, acrosslinking agent selected from toluene diisocyanate and triacetin, astabilizer selected from 2- nitrodiphenylamine and resorcinol, andballistic modifying means selected from the metallic compoundsconsisting of organometallic salts of the metals lanthanum, hafnium,tantalum, and barium, and oxides of said metals.

5. The nitrocellulosic propellant of claim 4 and wherein saidoxidizerplasticizer means is used in amounts from about 36 to about 84percent by weight of said propellant, said nitrocellulose binder-fuel isused in amounts from about to about 50 percent by weight of saidpropellant, said stabilizer is used in amounts from about 1 to about 2percent by weight of said propellant, said ballistic modifying means isused in amounts from about 2 to about 5 percent by weight of saidpropellant, and said cross-linking agent is used in amounts from about0.75 to about 8 percent by weight of said propellant.

6. The nitrocellulosic propellant of claim 5 and wherein saidoxidizerplasticizer means is nitroglycerine which is used in an amountof about 36.7 percent by weight of said propellant, said nitrocellulosebinderfuel is nitrocellulose which is used in an amount of about 50.3percent by weight of said propellant, said stabilizer is2-nitrodiphenylamine which is used in an amount of about 1.7 percent byweight of said propellant, said cross-linking agent is triacetin whichis used in an amount of about 8 percent by weight of said propellant,and said ballistic modifying means are barium salicylate and bariumbeta-resorcylate which are each used in amounts of about 1.66 percent byweight of said propellant.

7. The nitrocellulosic propellant of claim 5 and wherein saidoxidizer-plasticizer means are comprised of triethylene glycol dinitratein an amount of about 28.4 percent by weight of said propellant, butanetriol trinitrate in an amount of about 14.9 percent by weight of saidpropellant, trimethylenetrinitramine in an amount of about 39.6 percentby weight of said propellant, and nitroglycerine in an amount of about1.0 percent by weight of said propellant, said nitrocellulosebinder-fuel is nitrocellulose which :is used in an amount of about 10.6percent by weight of said propellant, said stabilizer is comprised ofresorcinol in an amount of about 0.50 percent by weight of saidpropellant and 2.- nitrodiphenylamine in an amount of 0.6 percent byweight of said propellant, said cross-linking agent is toluenediisocyanate in an amount of about 0.75 percent by weight of saidpropellant, and said ballistic modifying means is comprised of a 30/70blend of barium oxide and stannic oxide which is used in an amount ofabout 3.7 percent by weight of said propellant.

2. In a propellant composition of the type specified in claim 1 andwherein said metallic compounds selected are barium salicylate andbarium beta-resorcylate in equal amounts up to about 5 weight percent ofsaid composition.
 3. In a propellant composition of the type specifiedin claim 1 and wherein said metallic compounds selected are bariumoxides, BaO or BaO2, which are employed in a 30/70 ratio with stannicoxide, and which are employed in amounts up to about 5 weight percent ofsaid composition.
 4. A nitrocellulosic propellant comprised ofoxidizer-plasticizer means selected from nitroglycerine, triethyleneglycol dinitrate, butane triol trinitrate, and trimethylenetrinitramine,nitrocellulose binder-fuel, a cross-linking agent selected from toluenediisocyanate and triacetin, a stabilizer selected from2-nitrodiphenylamine and resorcinol, and ballistic modifying meansselected from the metallic compounds consisting of organometallic saltsof the metals lanthanum, hafnium, tantalum, and barium, and oxides ofsaid metals.
 5. The nitrocellulosic propellant of claim 4 and whereinsaid oxidizerplasticizer means is used in amounts from about 36 to about84 percent by weight of said propellant, said nitrocellulose binder-fuelis used in amounts from about 10 to about 50 percent by weight of saidpropellant, said stabilizer is used in amounts from about 1 to about 2percent by weight of said propellant, said ballistic modifying means isused in amounts from about 2 to about 5 percent by weight of saidpropellant, and said cross-linking agent is used in amounts from about0.75 to about 8 percent by weight of said propellant.
 6. Thenitrocellulosic propellant of claim 5 and wherein saidoxidizerplasticizer means is nitroglycerine which is used in an amountof about 36.7 percent by weight of said propellant, said nitrocellulosebinder-fuel is nitrocellulose which is used in an amount of about 50.3percent by weight of said propellant, said stabilizer is2-nitrodiphenylamine which is used in an amount of about 1.7 percent byweight of said propellant, said cross-linking agent is triacetin whichis used in an amount of about 8 percent by weight of said propellant,and said ballistic modifying means are barium salicylate and bariumbeta-resorcylate which are each used in amounts of about 1.66 percent byweight of said propellant.
 7. The nitrocellulosic propellant of claim 5and wherein said oxidizer-plasticizer means are comprised of triethyleneglycol dinitrate in an amount of about 28.4 percent by weight of saidpropellant, butane triol trinitrate in an amount of about 14.9 percentby weight of said propellant, trimethylenetrinitramine in an amount ofabout 39.6 percent by weight of said propellant, and nitroglycerine inan amount of about 1.0 percent by weight of said propellant, saidnitrocellUlose binder-fuel is nitrocellulose which is used in an amountof about 10.6 percent by weight of said propellant, said stabilizer iscomprised of resorcinol in an amount of about 0.50 percent by weight ofsaid propellant and 2-nitrodiphenylamine in an amount of 0.6 percent byweight of said propellant, said cross-linking agent is toluenediisocyanate in an amount of about 0.75 percent by weight of saidpropellant, and said ballistic modifying means is comprised of a 30/70blend of barium oxide and stannic oxide which is used in an amount ofabout 3.7 percent by weight of said propellant.